1. Technical Field
The present invention relates to liquid crystal devices and electronic apparatuses, and in particular, to a liquid crystal device including a reflective display region and a transparent display region.
2. Related Art
In general, there is a known semi-transparent reflective liquid crystal device that realizes reflective display in which a displayed item can be made visible by using reflected light based on external light or the like and transparent display in which a displayed item can be made visible by using transparent light such as backlight. Liquid crystal devices of the above type include, for example, a liquid crystal unit (see, for example, JP-A-2000-180881) including a plurality of pixels arranged in the form of a matrix, each pixel having a reflective display region and transparent display region formed thereon.
The liquid crystal unit has liquid crystal encapsulated between a pair of substrates made of glass. One substrate has a reflective layer formed thereon. Portions of the pixels on which the reflective layer is formed serve as reflective display regions, and other portions of the pixels on which the reflective layer is not formed serve as transparent display regions. In addition, in the reflective display region, the reflective layer is formed, with an interlayer insulating film provided on the substrate, and, in the transparent display region, the interlayer insulating film is not formed. In this structure, the thickness of the liquid crystal in the reflective display region is approximately a half of the thickness of the liquid crystal in the transparent display region. This can reduce a difference between optical modulation levels (retardation) for reflected light used in reflective display and transparent light used in transparent display, whereby their display forms can be optimized.
However, the liquid crystal unit including the reflective display region and the transparent display region has a problem of contrast decrease because outer edges of an interlayer insulating film formed in the reflective display region have a level difference and light leakage easily occurs due to misorientation of liquid crystal.
In particular, a large pixel area (aperture ratio) cannot be set in design because, since it is common to use a configuration in which one substrate has thereon a reflective layer and the other substrate has thereon a shielding layer for light shielding in the interpixel region, a large effect of the light leakage is produced by a possibility that a shift in pair of substrates may cause insufficient light shielding in the interpixel region by the shielding layer, and it is necessary to expand a shielding range of the shielding layer in order to prevent the effect.
For example, an example (comparative example) of the configuration of a liquid crystal device having the above configuration is discussed below. FIG. 6 is a partially enlarged plan view of a pixel structure in the example. As shown in FIG. 6, a pixel SP (subpixel) includes a reflective display region R and a transparent display region T. One substrate has wires 11 and switching elements 12 formed thereon. The switching elements 12 connect to the wires 11. For each switching element 12, a conductive contact portion 13 is provided. An insulating film 14 is formed on the wire 11 and the switching element 12. The insulating film 14 is formed in the reflective display region R, but is not substantially formed in the transparent display region T. The insulating film 14 has a reflective layer 15 formed thereon. The reflective layer 15 is formed of a thin film of a metal such as Al. The reflective layer 15 is also formed in the reflective display region R, but is not formed in the transparent display region T. The reflective layer 15 and the conductive contact portion 13 have a pixel electrode 16 formed thereon. The pixel electrode 16 is formed by a transparent conductor made of ITO (indium tin oxide) or the like. The pixel electrode 16 is formed both in the reflective display region R and in the transparent display region T.
In the above configuration, in an interpixel region between two adjacent pixels SP, a shielding layer 21X that is formed on the other substrate is formed. The shielding layer 21X can prevent light leakage from the interpixel region. The wire 11 also passes through the interpixel region, crossing the shielding layer 21X. In this structure, in particular, light leakage occurs due to orientation irregularity of liquid crystal since outer edges of the insulating film 14 have a level difference. In addition, the substrate that has the insulating film 14 formed thereon and the substrate that has the shielding layer 21X formed thereon are separate. Thus, there is a possibility that a shift in pair of the substrates may cause light leakage.
In addition, as described above, the shielding layer 21X covers the entirety of the periphery of the pixel SP. Thus, considering the effect of the pair of substrates, it is difficult to set the area of the pixel SP to be large. Accordingly, in particular, the reflective display region area cannot be sufficiently reserved, thus causing a problem in that reflective display looks dark.